NASA's Mariner 10 captured its first image of Mercury on March 24, 1974, from 3.34 million miles (5.38 million km) away.

Image Credit: NASA/JPL/USGS

On March 29, 1974, Mariner 10 captured this mosaic of Mercury from 37,300 miles (60,000 km) away, using over 140 TV frames taken two hours after its encounter.

Image Credit: NASA/JPL/USGS

Mercury transits the Sun about 13 times a century, with the last one on May 9, 2016.

Image Credit: NASA/JPL/USGS

NASA's MESSENGER spacecraft took a true-color image of Mercury on Oct. 6, 2008, revealing slight surface color differences

Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

This image was taken in October 2008 which shows the view over Mercury Horizon

Image Credit: NASA